Introduction
Fat is one of the 3 important macronutrients that the human body needs along with protein and carbohydrates and it’s a major source of energy. It aids in the absorption of fat-soluble vitamins (Vitamin A, D, E, K) and carotenoids. [1,2]
World Health Organization/ FAO have set the total fat intake to be at least 20 E% and is expressed as a percentage of total dietary energy (E%) or as grams per day for adults. [3]
Also, cholesterol intake should not ideally exceed 300 mg/day. [3]
Fats can be categorised as saturated, polyunsaturated, monounsaturated and trans fats. Polyunsaturated fats are further categorised into Omega 3 fatty acids (n-3) and Omega 6 fatty acids (n-6). Certain fatty acids are considered as essential as the body can’t synthesize them. [3,7]
Animal fats have a higher melting point and are solid at room temperature due to their high saturated fatty acids content[1]. However, plant fats (oils) tend to have a lower melting point and are, therefore, liquid at room temperatures because of their high content of unsaturated fatty acids, with the exception being coconut & palm kernel oil. [1,2,7]
Researchers have found a positive association between total saturated fats, trans fats intake and low-density lipoprotein (LDL) cholesterol concentration leading to an increased risk of coronary heart disease. [1,2,3] Similarly, high saturated fats intake can affect glucose/ insulin metabolism and can possibly increase the risk of diabetes [2]
Certain studies have also found a positive association between increased saturated and trans fats intake with obesity and body weight [2].
However monounsaturated and polyunsaturated fats are considered to be healthy fats and not linked to increased chronic disease risk [1,2].
There is also evidence from dietary intervention studies that replacing saturated fatty intakes with products rich in n-6 polyunsaturated fatty acids decreases the number of cardiovascular events[3].
- Fats are a slower source of energy than proteins or carbohydrates but the most energy-efficient form of food [2,3].
- Dietary fat consists primarily (98 per cent) of triacylglycerol and much of the triglycerides the body receives from food is transported to fat storehouses within the body [2].
- Dietary fat is emulsified with bile salts and phospholipids in the intestine to be hydrolyzed by pancreatic enzymes and finally absorbed completely [1].
- When fat is needed for fuel, free fatty acids from the liver and muscles are released into circulation to be taken up by various tissues where they are oxidised to provide energy [1,2].
- For a 70 kg man, Triacylglycerols constitute about 11 kg of his total body weight [6]. ??
- Usually, the daily fat intake is less than 1% of total fat reserves in the body, however, the fat stores contain about six times the energy of the protein stores [4].
- The glycogen and glucose stores provide enough energy to sustain biological function for about 24 hours, whereas the triacylglycerol stores allow survival for several weeks [6].
- The body deposits excess fat in the abdomen and in the skin to use when it needs more energy [7].
- As fatty acids are broken down through oxidation, carbon dioxide and water are released [1,2].
- Small amounts of ketone bodies are also produced and excreted in the urine [2].
Body Functions
Deficiency Symptoms
Side Effects of Overconsumption
When free fatty acid concentrations are relatively high, muscle uptake of fatty acids is also high [2].
Saturated fats and trans-fat can increase cholesterol and LDL levels which in turn can increase the risk of CHD [1].
High risk of obesity, cancer, and insulin resistance [1].
Special Considerations
Fats And Health
When low fats diet are replaced with high carbohydrates intake diets, it may change the metabolic profile leading to a reduction in high-density lipoprotein cholesterol (the good cholesterol), an increase in serum triacylglycerol concentration and changes in glucose/ insulin metabolism.[2]
These changes can possibly increase the risk of coronary heart disease and diabetes [2].
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